Method of casting metals



May 26, 1936. A. w. MORRIS 2,042,409

I METHOD OF CASTING METALS Filed Dec. 22, 19:53

INVIENTQR 'flLBERr W000 Mun/s TTORNEYS Patented May 26, 1936 UNITED STATES PATENT OFFICE 2,042,409 -.METHOD OF CASTING METALS Albert W ood Morris, Springfield, Mass. Application December 22, 1933, Serial No. 703,568 Claims. 01. 22-200) This invention relates to a method of casting particularly susceptible to contamination by the metals, particularly such metals as stainless exposure to an atmosphere other than one spesteel, malleable iron, grey iron, and alloy steel, cially prepared'for the particular metal. or castings of like metals that must be melted This is particularly true of metals at very high 5 at very high temperatures-say above 2000 F. temperature2000 F. and above. These. metals 5 The main object of the invention is to improve to which my invention relates commonly need and maintain a high metallurgical character in to be poured as the molds are being filled. I am the castings and avoid certain defects in castaware of the casting methods in which the mold ings of such metals as I have found to occur in are filled by suction i n r y pr s causthe methods of casting them as heretofore carin mol filling m v ment of m tal f m a suit- 10 ried out in practice. Other objects are to make able reservoir. Without going into the distincsavings in the business of casting such metals tions in detail, one skilled in the art knows that apart from and in addition to the superi r these prior casting methods are not suitable for metallurgical quality. general application; they are expensive; and they So far as I am aware, such metals have herea h ve not n ppar nt y nn be. used in a 15 tofore been handled as follows: They have been reatm y p aces wh h casting molds must melted within a furnace where the atmosphere e fil ed y the metal Pouring methods as in contact with the metal bath has been continguish fr m Suction, Dump n r immersion trolled or is ideal for the particular metal, as m thods. In any insta s t expense is too in an open-hearth, air, or electric furnace. The greatt With metals at temperatures above 20 molten metal has then been tapped" and t k 2000 F. substantially all casting is done under from the furnace to the molds, and the desired etal pouring steps to fi the molds- It is in pieces cast by pouring the metal into the molds. s fi ld t my inv nti particularly pp i s In practice I have found the following objecfor Obtaining improved l'esultstions to this common method. When the metal According to the main idea of my invention I 25 is taken from the furnace it cools rapidly before a Pou e metal in the usual Way to fill the being poured for casting. To offset this the mold, but I eliminate the time element in the metal is superheated, which is costly and bad common practice of transferring the metal from metallurgically. The pouring temperature for the furnace to position for pouring it into the, so different castings varies widely. The metal is ast molds- To do this I arry th casti I not ordinarily maintained at the best casting m l to h melting f rn in ert it in the temperature for the desired metallurgical results furnace, P the metal to ml the mold While in the casting, and the castings are not uniform. th mold and metal are in the furnace, d But perhaps more important than th dimculty, then either remove the mold with its casting as in the fact that temperatures vary widely befrom he furnaeei or I may remove t casting tween the furnace and the molds, there is t from the mold while it is still in the furnace. common difficulty of varying atmospheric c ndi- In such operations there is a time element in tions. When the metal is taken from the furnace the p of p rin he metal m the molten in a ladle it is soon exposed to and contaminated m s o fill h m ld, But this mold filling step 40 by the outside air both before pouring and as the y Pouring, takes Place While the mold is in the 40 metal is poured into the molds. And the molds furna a d h operation is possible w t are full of gases and air that also contaminate using any time during which molten metal the metal 'poured into their cavities, as do also is in transit between the furnace and any P t thesurfaces of the molds. These dimculties have outside of the furnace, and Wi exp n not been entirely overlooked. I am aware that the metal While being Poured o an atmospheric 45 much work has been done to improve the m thcondition different from that in the furnace. ods of handling hot metals between 'the furnaces The metal is P in the mold before e .metal and the molds and to prepare the molds for releaves the furnace, and in its cast condition the rceivi'ng the metal. 'But so far as I know, such metal is taken from the furnace either with or improved'methods are expensive and the results without the mold, as I w escribe- Thus, there 50 have not yet been satisfactory in metals melting is no chance for contamination of the molten at very high temperatures like steel, for in one metal by transportingit between the furnace and. way or another such metal is contaminated more the mold, and yet the mold is filled by the'deor less during the transition time between fursired and simple pouring step as from a ladle.

pace and mold or in the mold, and such metal is Furthermore, by inserting the mold into the 55 fective way for taking the hot metal under the best conditions. The .extremely h'mh temperature of the furnace will act instantly on said surfaces to dry them. It will also act instantly on all the gases imported in the mold cavities to the furnace and drive them out of the mold by such expansion. So before the mold can be filled these cavity gases (which cause so much trouble in the common casting practices) are driven out and dissipated in the much larger body of gases above the molten mass of metal. Thus the cavity atmosphere before pouring will be substantially. the same as the furnace atmosphere above the molten mass. That atmosphere is normally and suitably controlled according to the character of molten metal mass and is one that does not contaminate the. metal. It is an entirely different atmosphere. than obtains in the mold cavities and against the surfaces of the metal as treated in the common casting practise where the metal is carried from the furnace and poured from a, ladle to the mold.

In the accompanying drawing I have shown a cross-section through an open-hearth furnace wherein my method can be carried out.

My method may be carried out in practice by labor-saving apparatus of various kindscoordinated for the purpose, but it may be carried out by hand operations, and I want to emphasize that no expensive apparatus is needed. I herein refer to the hand method tools only, as the features of the new method may'best be understood without complicating the description with details of apparatus that would be used to save labor and time. The novel features of my preferred form of apparatus will be the subject matter of additional applications.

Referring to the drawing, I may melt the metal, stainless steel for example, in an openhearth furnace represented in the drawing at A. The melted metal rests on the hearth B and is at very high temperature when ready for casting, but need not be superheated. A characteristic of stainless steel is that given any opportunity it will absorb carbon with great avidity. It is an alloy and the less carbon it contains the less proportion of expensive elements is necessary in the alloy-to give the stainless results. It is also susceptible to contamination in other respects. This is one reason that its castings made in the ordinary way are frequently defective.

I leave the molten body of stainless steel in the furnace and do my casting in the furnace. The open-hearth furnace has a controlled atmosphere of hot gases passing over the surface of the melted bath. They are controlled so that the composition of the alloy will remain as wanted in the casting. Furthermore, these furnace gases maintain the desired temperature in the liquid, such temperature of the metal being easy to control when it is in a large mass and kept in the fur-- nace; I make use of this situation by holding the temperature and atmosphere above the furnace metal at the point best suited to casting. Ordinarily the furnace temperature needs to be kept far above the best casting point so as to com- .pensate for'the loss of heat when the metal is transported from the furnace to the molds. And when thus transported the metal is commonly poured in an atmosphere and at a. temperature, both outside and inside the mold, that are not so good as the furnace atmosphere and temperature.

With the temperature in the furnace held as stated, one workman may insert the mold held by a handle, and another the ladle held by a handle, through opposite doors (indicated at C) and made to open and close for my Purpose, in the furnace. The workman with the ladle dips metal from the furnace bath (avoiding any slag or dross on the top as is common in ladling hot metal) and pours the metal to fill the mold; or the ladle and mold may be inserted and operated from the same side of the furnace through one door only.. The doors being open will not affect the furnace gases to any substantial extent, as the air let in will follow the draft beyond the casting point.

The advantages in filling the mold by pouring the metal under these conditions are that its surfaces and cavities are nicely prepared by the heat of the furnace for receiving the casting, the time for the molten metal to leave its furnace body and get in to the mold is brought to a minimum, the exposure of the metal as it'is being poured is in the atmosphere of the furnace gases and at the same temperature, with a minimum risk of contamination. The pouring from ladle to mold can take place without any danger. of pouring too much as all excess drops immediately to the furnace bath, so that wastage or expense of remelting is avoided; the mold may be made to take this into account as by having exit passages to cause a mold circulation of hot metal until its cavities are filled solid. But the most important advantage is in the conditions surrounding the pouring operation for the transfer of metal from the body in the furnace to the cavity in the mold be emptied and the casting annealed with a minimum heat loss; and the less handling between the melting furnace and the annealing furnace, the better their metallurgical character can be safeguarded. The method can be used with the air type of furnace as well as the open-hearth, and in the same way. 7

The operation of my method with regard to the electric furnace is essentially the same as in the case of the open-hearth furnace, with this and possible additional advantage. A well known type of electric furnace" is of the rocking type. As the furnace rocks, in its normal operation for temperature transfer, the molten mass can be picked up by a pouring lip and the mold filled by the movement of the furnace as a workman holds the mold within the furnace.

The practical use of the method in a large way will involve the use of labor saving apparatus. For example, on opening the doors 0 of the openhearth furnace preparatory to casting, a series of successively arranged molds may be inserted and all be in the furnace. The heat there will prepare all the molds for pouringthe metal into them. They can be filled with labor saving ladle equipment and removed from the same door they went in or the opposite door. It will beof advantage in some instances to remove the castings while still in the furnace. This can be provided for by a shelf at the side of the hearth where 75 the casting can be left. And it will be ad tageous in some instances to pass the castings as they are removedfrom the furnace through a furnace door directly into an annealing .oven. One of the doors may be in a passage from the furnace to an annealing oven and opened to admit the casting from the furnace. The workman can shove it in from the opposite side or conveyers may be used. The advantage will be that the casting willnot be subjected to contting influences.

Stainless steel, malleable iron, grey iron, ordinary steel, and such very high melting point metals are to be cast by pouring the metal under this rrethod and preferably by use of labor saving apparatus which is not shown herein because not necessary to the method invention per se.

I claim: H

1. The method of casting high melting point metals which consists in continuously operating a furnace to maintain a substantially constant supply of metal at the right casting temperature and then casting in successive cycles by repeatedly inserting a mold inv the furnace, pouring the metal into the mold while in the furnace and entirely subjected to furnace heat and atmosphere, and removing the filled mold from the furnace, all without interrupting the furnace operation.

2. The method of casting high melting point metals which consists in maintaining metal at the right casting temperature under a controlled atmosphere in the melting chamber of a furnace," and then casting in successive cycles by'repeatedly inserting a mold above the molten metal in such chamber. and filling the mold by pouring the metal while in said chamber under the atmospheric conditions of the chamber where the metal is maintained for casting, said successive cycles being carried on from the substantially constant metal supp maintained in the furnace.

3. The method of casting high melting point metals which consists in maintaining a large amount of metal in a furnace hot enough to furnace, in which the highest melting temperacast, moving a casting mold of very small capacity compared to the furnaceto a position inside the furnace adjacent the metal; and pouring a very small. part of the metal from: the furnace into the mold to fill it under-the same 5 temperature and atmospheric conditions for the pouring operation as for the furnace operation and repeating the casting steps with successive molds while maintaining the same furnace operation on the large amount of metal to have it ready at all times for filling the said small molds as they are successively filled.

4. The method of casting high melting point metals, which consists in melting a large body of metal in a furnace, holding the temperature of the molten metal at substantially the best point for casting purposes, controlling the at-[ mosphere of the furnace in contact with the surface of the metal substantially free of contaminating influence on the metal, intermit- 2o tently locating a mold in the furnace long enough for its cavity to be filled with the furnace atmosphere, pouring metal from the body in the furnace to fill the mold while in the furnace, and then removing the mold and its casting fromgs the furnace without interrupting the furnace operation on the remaining metal.

5. The method of casting metals from a furnace such as an open-hearth, air, or electric so tures are used, which consists in melting steel, iron, refractory alloys, and such high melting point metals, and raising such metal to approximately the best casting temperature and main taining it at such point, intermittently inserting a casting mold into the furnace adjacent the level of the molten metal so as to have its cavity atmosphere and surfaces brought to the same temperature as the metal, and then pouring a small part of the metal with a ladle to fill the 40 mold, andremoving it, and repeating the casting cycle while maintaining a'large body of the metal under the furnace operation while the successive casting cycles are being carried on.

ALBERT woon MORRIS. 

